1. Field of the Invention
The present invention relates to a microplate liquid handling system and, more particularly, to a microplate liquid handling system for simultaneously delivering liquid reagent, liquid specimen, etc. to a plurality of desired wells for specimen/reagent reaction arranged in a microplate in n×m matrix.
2. Description of the Related Art
A microplate liquid handling system has conventionally been known which is used to deliver reagent, specimen, etc. to desired ones of a plurality of wells formed in a microplate. The microplate liquid handling system has a dispensing mechanism and a moving mechanism, and the dispensing mechanism is equipped with a cylinder having a nozzle. Mounted to the nozzle is a dispensing tip, through which liquid can be sucked and discharged. The cylinder is equipped with a plunger for sucking liquid into the dispensing tip mounted to the nozzle and for discharging liquid from the interior of the dispensing tip.
As disclosed, for example, in JP 8-271528 A and JP 5-232124 A, the moving mechanism is capable of moving the nozzle to an appropriate position above a desired well in the microplate, and the dispensing mechanism can be moved in the lateral, longitudinal, and vertical directions (the X-, Y-, and Z-axis directions) above the microplate. Generally speaking, arranged in the microplate are 96 wells in 12×8 matrix, and so-called dispensing is conducted, that is, reagent or specimen is delivered to a desired well from a dispensing tip mounted to the nozzle of the cylinder of the dispensing mechanism, so that reagent-specimen reaction or the like is effected in the well.
There are four types of microplate liquid handling system: 12-gang type, 8-gang type, single-gang type, and 96-gang type. In a 12-gang type microplate liquid handling system, the nozzles of twelve cylinders arranged in parallel and in a straight line in the longitudinal direction of the microplate are operated in synchronism with each other, and it is possible to perform suction or discharge of liquid such as reagent collectively on the dispensing tips mounted to the twelve nozzles. For example, it is possible to simultaneously discharge reagent onto each of the specimens in the plurality of wells arranged longitudinally in a row in the microplate.
Similarly, in an 8-gang type microplate liquid handling system, eight nozzles arranged in parallel and in a straight line in the lateral direction of the microplate are operated in synchronism with each other, and it is possible to perform suction or discharge of liquid such as reagent collectively on the dispensing tips mounted to the eight nozzles. In a 96-gang type microplate liquid handling system, 96 nozzles arranged in 12×8 matrix are operated in synchronism with each other, and it is possible to perform suction or discharge of liquid such as reagent collectively on the dispensing tips mounted to the 96 nozzles and to discharge reagent or the like simultaneously onto all the 96 wells in the microplate. In a single-gang type microplate liquid handling system, a single nozzle is solely operated.
When discharge is to be performed simultaneously on a plurality of wells in the above conventional 12-gang and 8-gang microplate liquid handling systems, there is a limitation in terms of discharging direction. That is, in the case of the 12-gang type microplate liquid handling system, it is only possible to perform simultaneous discharge on a plurality of wells arranged in a row in the longitudinal direction, and it is impossible to perform simultaneous discharge on a plurality of wells arranged in a row in the lateral direction. In the case of the 8-gang type microplate liquid handling system, it is only possible to perform simultaneous discharge on a plurality of wells arranged in a row in the lateral direction, and it is impossible to perform simultaneous discharge on a plurality of wells arranged in a row in the longitudinal direction.
In the case of the 96-gang type microplate liquid handling system, suction and discharge are performed collectively on all the 96 wells in the microplate, so that it is impossible to dispense liquid onto a particular longitudinal row or to perform automatic dispensing on a particular lateral row. That is, after performing dispensing on a longitudinal row, the dispensing tip must be replaced manually before dispensing can be performed on a lateral row. In the case of the single-gang type microplate liquid handling system, it is possible to perform suction or discharge on an arbitrary one of the 96 wells whether it is in the longitudinal or lateral direction of the microplate. However, it is impossible to perform suction/discharge operation simultaneously and collectively on a plurality of wells. Thus, control of time, which is an important factor in drug metabolic reaction, involves a problem. For example, the reaction time differs from well to well.
Thus, none of the above-mentioned conventional microplate liquid handling system is capable of performing a drug metabolic reaction test or the like in which it is necessary to automatically conduct collective suction/discharge operation in both the longitudinal and lateral directions in a single microplate.